43 



sand, wliicli in the form of a minor escarpment skirts the 

 river for a few miles to the eastward and sweeps round 

 Lake Bonney, where the sand is white and exceedingly large 

 in grain. 



As to the areas occupied by the Xewer and Older Tertiary 

 deposits respectively, the information in my possession is too- 

 fragmentary to allow of an attempt at definition, though it 

 may be useful to record it. 



West side of the Biver Murray. — At the Half-way House, on 

 the edge of the mallee scrub on' the road to Blanchetown from 

 Truro, a well-sinking commencing m red drift penetrated 

 oyster banks at 110 feet from the surface. 



The Government Well and other sinkings adjacent prove 

 that the subter-structure of the Desert is Older Tertiary. 



The most distant locality from the river at which Older 

 Tertiary fossils have been obtained is in a well sinking at the 

 north-east corner of County Burra, forty- seven miles due north 

 from Morgan. 



North side of the Biver Murray. — The following section 

 indicates the northern extension of the Xewer Tertiary. 



Well-sinking at Oakvale, about ten miles due west from 74- 

 milepost measured from the River Murray, on the boundary 

 between South Australia and New South Wales (communi- 

 cated by Mr. D. Cudmore) : — 



At 175 feet, yellow ochreous clay. 



At 180 " grey pipeclay. 



At 190 " id. 



At 196 " black clay, with much quartzose sand. 



Doubtlessly the whole of the depressed area about the Lower 

 Darling is constituted of Newer Tertiary. 



South side of the Biver Murray. — The geological structure of 

 the country which intervenes between the river at the Boun- 

 dary and the Tatiara is, so far as I know, quite blank ; but it 

 is not unreasonable to suppose that the Newer Tertiary at 

 these places is coterminous. The Tatiara is an oasis on the 

 edge of the mallee scrub, in the one direction, and of the heath- 

 lands of the South-East in the other ; it owes its reputation to 

 deep loamy soils, the upper members of an extensive lacustrine 

 deposit, as is partly revealed by a well-sinking at Border 

 Town, of which the following is a summary of the facts : — 



Pipeclay 30 feet. 



Diatomaceous earth ... ... 21 " 



Bituminous shale and clay ... 40 " 



Total 91 feet. 



